Several patents have issued in recent years on machines for making, filling and sealing containers on a high volume basis. In the specific field of bag packaging, U.S. Pat. Nos. 2,877,609; 2,923,111; 3,269,278; 3,381,446; 3,462,913; 3,492,783; 3,559,874; and 3,791,573 are typical of patents disclosing machines and methods for filling and sealing bags on a high volume basis.
In each of the above noted patents a web of flexible packaging material, commonly a thermoplastic material, is folded longitudinally and provided with spaced, transverse sealing lines, typically heat seal lines, to divide the web into a series of interconnected compartments which are thereafter filled with the desired product and their open mouths sealed, again usually by means of a heat seal.
In some of these disclosures, for example, U.S. Pat. No. 3,492,783, the transverse seal lines extend from the bottom edge to a point short of the top edge to provide a pair of continuous free edges, apparently to permit the upper edges to be spread by a plow-like member to facilitate insertion of a filling nozzle into each of the compartments.
In others, such as U.S. Pat. Nos. 3,559,874 and 3,791,573, the tube is split after the transverse heat seals are formed to provide a pair of free edges which are spread open, similarly to the approach in U.S. Pat. No. 3,492,783, to allow filling.
While each of the systems disclosed in the above noted patents would appear to offer advantages over a manual packaging operation, it will be apparent that no attempt is made in such systems to form an aseptic package, that is one that is free of pathogenic microorganisms. Thus, when a product such as milk is packaged in systems of this type, it is essential that it be refrigerated in order to provide any appreciable shelf life. It will be appreciated, however, that in many countries refrigeration is a rarity and, as a consequence milk, a high protein food, is generally unavailable.
In applicant's above noted U.S. Pat. No. 3,813,845 an attempt is made to provide sterile packages by providing multiple pipes at the filling section of the filling and sealing machine disclosed therein and injecting into the web of bags through one of the multiple pipes a sterilizing gas which is thereafter displaced by the product deposited in the bags by one or more of the multiple pipes.